docs: def visit_inheritance_diagram(inner_func):
      """
      This is just a wrapper around html/latex_output_graph to make it
      easier to handle errors and insert warnings.
      """
      def visitor(self, node):
          try:
              content = inner_func(self, node)
          except DotException, e:
              # Insert the exception as a warning in the document
              warning = self.document.reporter.warning(str(e), line=node.line)
              warning.parent = node
              node.children = [warning]
          else:
              source = self.document.attributes['source']
              self.body.append(content)
              node.children = []
      return visitor